A Tricky Transition to IPv6

11/07/2009 2:00 AM Eastern

For such a nerdy, network-y name , IPv6 rides with some pretty colorful language. Without it, for instance, the global Internet faces “IP address exhaustion.” With it, we could theoretically affix an IP address to “every atom on the surface of Earth.”

But getting to IPv6 (from IPv4) won’t be trivial, engineers said over and over during the recent SCTE Cable Tec Expo. (And in engineer-speak, “non-trivial” is several shades darker than “really challenging.”)

We’re running out of IP addresses, and pretty much everything needs one. Bad news for any TV, PC or handheld screen craving an Internet connection.

Two entities are the keepers of Internet Protocol addresses: IANA, the Internet Assigned Numbers Authority, and ARIN, the American Registry for Internet Numbers. IANA runs dry by the end of next year; ARIN in 2012.

That’s why it’s good that so many IPv6 addresses are on deck — except for the largesse of getting backbone, access and in-home networks ready for them. Turns out that the coexistence of IPv4 and IPv6 addresses is … well … non-trivial.

From a consumer perspective, if the bits moving to or from a screen affixed to an IPv6 addresses smack into any gear the route that only knows IPv4, whatever that consumer was looking at won’t load right, at least the first time.

For the caretakers of broadband, going to IPv6 requires careful planning and phasing. (This particular point is consistently bracketed in “I can’t emphasize this enough” admonitions from engineers working on it.) It’ll seem like a slowdown, or a glitch, and it will happen on the day you hit every red light on the way to work, while feeling like you’re getting a cold.

The transition itself can go down in at least three ways. Safest, from a consumer perspective, is “dual stacking,” which means gear that speaks both v4 and v6.

Or, there’s tunneling, also known as encapsulation, which sidelines into terminology like “6to4,” “ISATAP,” and “Teredo.” All describe different ways of making the new stuff look and act like the old stuff.

Also an option: Network address translation, or NAT, which does the opposite — it translates v4 addresses into v6 addresses.

Other, more tactical considerations: Getting the actual IPv6 address allocations; deciding where to start transitioning — core or edge; picking routing protocols; prepping all back-office functions; and making sure all bases are covered so that the new, v6 stuff doesn’t put the existing, v4 stuff at risk.

Bottom line, and to quote Comcast’s John Brzozowski, chief IPv6 architect and principal engineer: “This is no one-man show. Everyone in your company has something to do with the success of your v6 program.”